Kids Lose Bone After Bariatric Surgery

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Obese adolescents lost significant amounts of bone mineral content during

the first two years after bariatric surgery, results of a retrospective case

review showed.

Bone mineral content decreased by 7.4% during the period reviewed. Weight,

bone mineral content, and bone mineral density (BMD) z score all declined

significantly after surgery (*P*<0.0001). However, the z score remained

above average.

Correlation analysis showed a significant association between weight loss

and change in bone mineral content (*P*=0.02), Anne-Marie D. Kaulfers, MD,

of Cincinnati Children's Hospital Medical Center, and colleagues reported

online in *Pediatrics*.

" Although the predicted bone density was appropriate for age two years after

surgery, longer follow-up is warranted to determine whether bone mass

continues to change or stabilizes, " they wrote in conclusion.

Mirroring the trend in adults, obesity in adolescents has increased over the

past decade, affecting an estimated 18.1% of children (*JAMA * 2010; 303:

242-249). The ineffectiveness of behavior modification has led a growing

number of adolescents to bariatric

surgery<http://www.medpagetoday.com/MeetingCoverage/ASMBS/20903>to

achieve weight loss.

Among bariatric options, Roux-en-Y gastric bypass has achieved dramatic

weight loss in adolescents, averaging 58% to 73% during the first year after

surgery, Kaulfers and co-authors wrote. However, the long-term consequences

of the surgery in children and adolescents remain unclear.

Loss of bone mineral at a time when young people should be reaching peak

bone mass could put future bone health at risk, they continued.

To explore the issue, Kaulfers and colleagues reviewed medical records of

102 young patients who had laparoscopic Roux-en-Y gastric bypass surgery

from 2001 to 2008. To be considered for the surgery, patients had to meet

five criteria:

- Unsuccessful weight-loss attempts lasting more than six months

- Body mass index (BMI) >35

- One or more obesity-related comorbidities

- Completion of all or most linear growth

- Acceptable psychologic evaluation

Patients underwent dual x-ray absorptiometry (DXA) before surgery and then

every three to six months afterward for two years. For each patient,

investigators calculated whole-body bone mineral content and BMD z score.

The final analysis included 61 patients, 51 of whom were female and whose

age averaged 17. The primary reason for exclusion was a baseline weight that

exceeded the limits of the densitometry machine.

Preoperative BMI averaged 54 to 55, weight averaged 335 pounds among girls

and 367 pounds in boys, and height averaged 65.9 inches in girls and 68.6

inches in boys.

Baseline characteristics included nonalcoholic fatty liver disease in 18%,

hypertension in 30%, depression in 33%, sleep apnea in 63%, type 2 diabetes

in 11%, and polycystic ovary syndrome in 28% of the girls.

On average the patients had three DXA scans during follow-up; all of the

study participants had at least two scans. The last scan occurred an average

of 13.9 months after surgery (range of 2.8 to 26.8 months).

The predicted weight loss was 41.4 pounds at six months, 58.4 pounds at 12

months, 61 pounds at 18 months, and 49.2 pounds at 24 months.

The preoperative whole-body bone mineral content averaged 2,692 g,

decreasing to 2,552 g after one year (5.2%) and to 2,494 g at two years

(7.4%).

Weight and bone mineral content declined in a curvilinear manner over time (

*P*<0.0001), whereas BMD z score declined in a linear fashion (*P*<0.0001).

The patients' mean BMD z score decreased from 1.5 at baseline to 0.1 over

the two-year follow-up period, BMD z score remained above average for the

cohort.

In contrast to bone mineral content, BMD z score did not correlate

significantly with weight change (*P*=0.73).

" It is reassuring that these patients began with greater BMD z score than

expected, and BMD did not typically fall below average during the two years

after surgery, " the authors wrote in their discussion.

" However, the clinical consequences of losing bone mass after Roux-en-Y

gastric bypass performed in the adolescent years are unknown. Therefore,

these adolescents need to be followed long-term to determine if the decrease

in BMD z score continues and increases their risk for future fractures.

LINK<http://www.medpagetoday.com/Pediatrics/Obesity/25556?utm_content= & utm_mediu\

m=email & utm_campaign=DailyHeadlines & utm_source=WC & em=nro1comcast (DOT) net>

*Primary source: *Pediatrics

Source reference:

Kaulfers AD " Bone loss in adolescents after bariatric surgery "

*Pediatrics*2011; DOI:10.1542/peds.2010-0785.

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Ortiz, MS, RD

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